zephyr: serial recovery: Missing required hash field in state of images response

[nordicjm]

On https://docs.zephyrproject.org/latest/services/device_mgmt/smp_groups/smp_group_1.html it states that for the "get image state" response, hash is a required field, however in mcuboot with serial recovery, this field is in fact not sent, therefore either the field should be sent or the documentation needs to be updated to specify that it is not a required field in the response.

This issue has been opened in zephyr also: zephyrproject-rtos/zephyr#54064

[pepe2k]

@nordicjm I have a hacky patch with support for including hash in my local tree (see: https://pastebin.com/EGFdUA7L). To apply it cleanly, include this first: #1507

Cheers,
Piotr